This will simplify the work on follow up CLs a lot

BUG=angleproject:516

Change-Id: Ie8374ec28fce2e01e76c711a4d280e1ed004a21f
Reviewed-on: https://chromium-review.googlesource.com/283380Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>